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Allow SAML username provider plugins (#6411)

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Andrew Morgan 2019-12-10 17:30:16 +00:00 • committed by GitHub
parent b2dcddc413
commit 4947de5a14
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5 changed files with 414 additions and 103 deletions
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200
synapse/handlers/saml_handler.py
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@ -13,20 +13,36 @@
# See the License for the specific language governing permissions and
# limitations under the License.
import logging
import re
from typing import Tuple
import attr
import saml2
import saml2.response
from saml2.client import Saml2Client
from synapse.api.errors import SynapseError
from synapse.config import ConfigError
from synapse.http.servlet import parse_string
from synapse.rest.client.v1.login import SSOAuthHandler
from synapse.types import UserID, map_username_to_mxid_localpart
from synapse.types import (
UserID,
map_username_to_mxid_localpart,
mxid_localpart_allowed_characters,
)
from synapse.util.async_helpers import Linearizer
logger = logging.getLogger(__name__)
@attr.s
class Saml2SessionData:
"""Data we track about SAML2 sessions"""
# time the session was created, in milliseconds
creation_time = attr.ib()
class SamlHandler:
def __init__(self, hs):
self._saml_client = Saml2Client(hs.config.saml2_sp_config)
@ -37,11 +53,14 @@ class SamlHandler:
self._datastore = hs.get_datastore()
self._hostname = hs.hostname
self._saml2_session_lifetime = hs.config.saml2_session_lifetime
self._mxid_source_attribute = hs.config.saml2_mxid_source_attribute
self._grandfathered_mxid_source_attribute = (
hs.config.saml2_grandfathered_mxid_source_attribute
)
self._mxid_mapper = hs.config.saml2_mxid_mapper
# plugin to do custom mapping from saml response to mxid
self._user_mapping_provider = hs.config.saml2_user_mapping_provider_class(
hs.config.saml2_user_mapping_provider_config
)
# identifier for the external_ids table
self._auth_provider_id = "saml"
@ -118,22 +137,10 @@ class SamlHandler:
remote_user_id = saml2_auth.ava["uid"][0]
except KeyError:
logger.warning("SAML2 response lacks a 'uid' attestation")
raise SynapseError(400, "uid not in SAML2 response")
try:
mxid_source = saml2_auth.ava[self._mxid_source_attribute][0]
except KeyError:
logger.warning(
"SAML2 response lacks a '%s' attestation", self._mxid_source_attribute
)
raise SynapseError(
400, "%s not in SAML2 response" % (self._mxid_source_attribute,)
)
raise SynapseError(400, "'uid' not in SAML2 response")
self._outstanding_requests_dict.pop(saml2_auth.in_response_to, None)
displayName = saml2_auth.ava.get("displayName", [None])[0]
with (await self._mapping_lock.queue(self._auth_provider_id)):
# first of all, check if we already have a mapping for this user
logger.info(
@ -173,22 +180,46 @@ class SamlHandler:
)
return registered_user_id
# figure out a new mxid for this user
base_mxid_localpart = self._mxid_mapper(mxid_source)
# Map saml response to user attributes using the configured mapping provider
for i in range(1000):
attribute_dict = self._user_mapping_provider.saml_response_to_user_attributes(
saml2_auth, i
)
suffix = 0
while True:
localpart = base_mxid_localpart + (str(suffix) if suffix else "")
logger.debug(
"Retrieved SAML attributes from user mapping provider: %s "
"(attempt %d)",
attribute_dict,
i,
)
localpart = attribute_dict.get("mxid_localpart")
if not localpart:
logger.error(
"SAML mapping provider plugin did not return a "
"mxid_localpart object"
)
raise SynapseError(500, "Error parsing SAML2 response")
displayname = attribute_dict.get("displayname")
# Check if this mxid already exists
if not await self._datastore.get_users_by_id_case_insensitive(
UserID(localpart, self._hostname).to_string()
):
# This mxid is free
break
suffix += 1
logger.info("Allocating mxid for new user with localpart %s", localpart)
else:
# Unable to generate a username in 1000 iterations
# Break and return error to the user
raise SynapseError(
500, "Unable to generate a Matrix ID from the SAML response"
)
registered_user_id = await self._registration_handler.register_user(
localpart=localpart, default_display_name=displayName
localpart=localpart, default_display_name=displayname
)
await self._datastore.record_user_external_id(
self._auth_provider_id, remote_user_id, registered_user_id
)
@ -205,9 +236,120 @@ class SamlHandler:
del self._outstanding_requests_dict[reqid]
@attr.s
class Saml2SessionData:
"""Data we track about SAML2 sessions"""
DOT_REPLACE_PATTERN = re.compile(
("[^%s]" % (re.escape("".join(mxid_localpart_allowed_characters)),))
)
# time the session was created, in milliseconds
creation_time = attr.ib()
def dot_replace_for_mxid(username: str) -> str:
username = username.lower()
username = DOT_REPLACE_PATTERN.sub(".", username)
# regular mxids aren't allowed to start with an underscore either
username = re.sub("^_", "", username)
return username
MXID_MAPPER_MAP = {
"hexencode": map_username_to_mxid_localpart,
"dotreplace": dot_replace_for_mxid,
}
@attr.s
class SamlConfig(object):
mxid_source_attribute = attr.ib()
mxid_mapper = attr.ib()
class DefaultSamlMappingProvider(object):
__version__ = "0.0.1"
def __init__(self, parsed_config: SamlConfig):
"""The default SAML user mapping provider
Args:
parsed_config: Module configuration
"""
self._mxid_source_attribute = parsed_config.mxid_source_attribute
self._mxid_mapper = parsed_config.mxid_mapper
def saml_response_to_user_attributes(
self, saml_response: saml2.response.AuthnResponse, failures: int = 0,
) -> dict:
"""Maps some text from a SAML response to attributes of a new user
Args:
saml_response: A SAML auth response object
failures: How many times a call to this function with this
saml_response has resulted in a failure
Returns:
dict: A dict containing new user attributes. Possible keys:
* mxid_localpart (str): Required. The localpart of the user's mxid
* displayname (str): The displayname of the user
"""
try:
mxid_source = saml_response.ava[self._mxid_source_attribute][0]
except KeyError:
logger.warning(
"SAML2 response lacks a '%s' attestation", self._mxid_source_attribute,
)
raise SynapseError(
400, "%s not in SAML2 response" % (self._mxid_source_attribute,)
)
# Use the configured mapper for this mxid_source
base_mxid_localpart = self._mxid_mapper(mxid_source)
# Append suffix integer if last call to this function failed to produce
# a usable mxid
localpart = base_mxid_localpart + (str(failures) if failures else "")
# Retrieve the display name from the saml response
# If displayname is None, the mxid_localpart will be used instead
displayname = saml_response.ava.get("displayName", [None])[0]
return {
"mxid_localpart": localpart,
"displayname": displayname,
}
@staticmethod
def parse_config(config: dict) -> SamlConfig:
"""Parse the dict provided by the homeserver's config
Args:
config: A dictionary containing configuration options for this provider
Returns:
SamlConfig: A custom config object for this module
"""
# Parse config options and use defaults where necessary
mxid_source_attribute = config.get("mxid_source_attribute", "uid")
mapping_type = config.get("mxid_mapping", "hexencode")
# Retrieve the associating mapping function
try:
mxid_mapper = MXID_MAPPER_MAP[mapping_type]
except KeyError:
raise ConfigError(
"saml2_config.user_mapping_provider.config: '%s' is not a valid "
"mxid_mapping value" % (mapping_type,)
)
return SamlConfig(mxid_source_attribute, mxid_mapper)
@staticmethod
def get_saml_attributes(config: SamlConfig) -> Tuple[set, set]:
"""Returns the required attributes of a SAML
Args:
config: A SamlConfig object containing configuration params for this provider
Returns:
tuple[set,set]: The first set equates to the saml auth response
attributes that are required for the module to function, whereas the
second set consists of those attributes which can be used if
available, but are not necessary
"""
return {"uid", config.mxid_source_attribute}, {"displayName"}